The Battle of Demetrias was a sea engagement fought at Volos in Greece in the early 1270s between a Byzantine fleet and the assembled forces of the Latin barons of Euboea (Negroponte) and Crete. The battle was fierce, and initially in favour of the Latins, but the timely arrival of Byzantine reinforcements tipped the scale, resulting in a crushing Byzantine victory. Background In the aftermath of the Fourth Crusade and the dissolution of the Byzantine Empire in 1204, the Aegean Sea, once Byzantium's naval heartland, was dominated by a hodgepodge of Latin principalities, protected by the naval might of the Republic of Venice. Following the recapture of Constantinople and the restoration of the Byzantine Empire in 1261, one of the chief priorities of Emperor Michael VIII Palaiologos () was the defence of his capital from a Venetian attack. Consequently, he sought an alliance with Venice's major antagonist, the Republic of Genoa, while he began building up his own navy. With the aid of his newly constructed fleet, in 1263 Palaiologos sent an expedition to the Morea, against the Principality of Achaia. At the verge of victory, the Byzantine land forces were surprised and defeated, while the joint Byzantine-Genoese fleet was dealt a severe blow by a numerically inferior Venetian fleet at the Battle of Settepozzi. This led to the abandonment of the Genoese alliance by Michael, who initiated a rapprochement with Venice, leading to a five-year peace treaty in 1268. With the neutralisation of the Republic of Venice, the major threat to imperial interests in the Aegean were the Lombard corsairs based at Negroponte. The island was repeatedly attacked by the Byzantine fleet under Alexios Philanthropenos, but no permanent gains were achieved. Only from 1273, with the aid of the Latin renegade Licario, did Byzantine forces make headway, capturing a number of fortresses on the island. In the early 1270s (the exact date is uncertain, most recent scholars favour 1272/3 or 1274/5), Michael VIII Palaiologos launched a major campaign against John I Doukas, ruler of Thessaly. It was to be headed by his own brother, the despotes John Palaiologos. To prevent any aid coming to him from the Latin principalities, he also dispatched a fleet of 73 ships, led by Philanthropenos, to harass their coasts. The Byzantine army, however, was defeated at the Battle of Neopatras with the aid of troops from the Duchy of Athens. At the news of